The paper describes a program of lateral load tests on six drilled shafts installed in a loess deposit at a site in Wyandotte County, Kansas. The lateral load test data, along with site characterization data that included CPT data, were used to develop a hyperbolic model to generate p-y curves for use in lateral load analyses in cemented soils. The model should be applicable to many “c-phi” soils (soils with both a cohesion intercept and a friction angle, such as cemented soils). Degradation of the static soil model to account for cyclic loading effects is included in the new model.
This paper was originally published in the DFI Journal,Vol. 5 No. 2, December 2011, the bi-annual Journal of the Deep Foundations Institute. DFI is an international technical association of firms and individuals involved in the deep foundations and related industry. The DFI Journal is provided to DFI members at no cost electronically or can be purchased in print at www.dfi.org.
This paper is one of several papers and articles published form a series of research projects by KU and the Kansas DOT. Some of the previous work can be found at these links:
As massive concrete piers rise from the Mississippi river in southeast Minnesota, people have begun to take notice of what will become the longest free-standing tied-arch bridge in North America. A unique project in several respects, the new Hasting bridge has recently been featured in articles on the websites of ENR and Roads & Bridges. The ENR article is a republication of an article that originally appeared in the Minneapolis Star Tribune highlighting the construction process of the last year, with particular focus on the process of constructing the river piers. The Roads & Bridges article is a more technically in-depth piece written by the lead bridge engineer Vincent T. Gastoni, P.E., of Parsons Transportation Group. Both articles discuss some of the many geotechnical changes faced on this project. This excerpt from Roads & Bridges is a concise description of the pier foundations and some of the reasoning behind their selection:
The main river piers are concrete delta-style frames with the tied-arch superstructure fully framed into the pier through the knuckle connection. The stiffness of the foundation system was then integral to the overall force effects in the structure. The north pier is located in 190 ft of soft soils overlaying rock and supported on unfilled 42-in. driven steel pipe piles. Drilled shafts were investigated early but were not cost-effective, impacted the schedule and presented a risk to the existing bridge due to potential caving effects. Statnamic pile load testing was used to validate the vertical capacity and lateral performance of the 42-in. piles. The south pier footing is close to the rock surface; however, the rock was deeper, more sloped than expected, and the originally planned spread footing was changed to short drilled shafts during the final design. Dan Brown & Associates provided the team with geotechnical analysis and recommendations.
Our Tim Siegel pointed out that the statement “It’s a marvel of engineering that requires ingenious construction techniques, most of which are invisible to the drivers whizzing by overhead,” from the Star Tribune, is an accurate description of how our work as foundation designers and constructors is often viewed. Although much of the ingenuity and innovation that goes into the geotechnical aspects of projects often goes unnoticed by the general public, it is certainly refreshing to see articles like these. For us at DBA, it is even more refreshing to see our efforts credited by name as they were in the article by Vince when he wrote, “Dan Brown & Associates provided the team with geotechnical analysis and recommendations.”
For a design-build project with so many different geotechnical components (driven piles, drilled shafts, spread footings, retaining walls, a column-supported embankment, and light weight fill), it is hard to believe that our role as the lead geotechnical engineer is nearing completion just a little over a year after construction began. At this point, the only foundations that have yet to be constructed are some of the rock bearing spread footings at the south approach. DBA will also monitor instrumentation installed in the column-supported embankment for the next two years.
Greetings to all Terzaghi fans! Yes, it is that time of year again, where our thoughts turn to the anniversary of the birth of one of the greats in our field.
Last year I had a football themed post (college football, in case you were wondering…and that is American football for our fans outside the U.S.) since Terzaghi’s birthday was on a Saturday. Since I am not a big pro football fan, and since I used football last year, I figured I would do something different for this year’s weekend post.
It should be no surprise that Prof. Terzaghi was very active and one of the key figures in the formation and success of ISSMGE, which began as the International Conference on Soil Mechanics and Foundation Engineering (ICSMFE). Many of the giants of soil mechanics and geotechnical engineering on which we base al of our work were instrumental in the start of ICSMFE and its impacts on our profession. As for that time in history (1936) and how it was important to our field:
The time had come to hold a Conference aimed at exchanging and sharing information on Earth and Foundation Engineering.
It was Professor Arthur Casagrande (assistant professor of Harvard University) who sensed the timing, conceived the idea and carried out the herculean task of running the conference all the way through, in his role of Secretary General, with K. Terzaghi (Professor of Technical University of Vienna and visiting Professor of Harvard University) as Chairman. Professor Peck once remarked “Our Society owes an enormous debt to Arthur Casagrande for his conviction that the time was right for the International Conference and to his tremendous efforts to organize it“.
Since the first ICMSFE was so successful, it became clear that the Conference should not remain a one-off event but should, instead, be continued within a few years, possibly being held in Holland where earthwork engineering is so crucial to the country.
It was also requested to set up a permanent international organization. Thus it was decided to establish International Committees consisting of National Committees with K. Terzaghi as President and A. Casagrande as Secretary. It was also decided that at the next Conference the International Committees would submit the draft of the Constitution and of the By-laws, which are essential for the Society to become a permanent organization.
There was at that time a widespread awareness that it was the moment to set up a common denominator institution that would group engineers with diverse backgrounds but involved in our discipline.
Portion of group photo from 1st ICSMFE, 1936. (From ISSMGE Bulletin Vol 5, No 4, August 2011, p3)
Photo of Terzaghi addressing the opening session of the 4th ICSMFE, 1957. (From ISSMGE Bulletin Vol 5, No 4, August 2011, p7)
And the rest, as the saying goes, is history!
As an editorial note on the first year, Ishihara and Jamiolkowski offer this observation:
It is commonly recognized that K. Terzaghi is the originator of modern soil mechanics and foundation engineering and therefore father of our profession. After tracing the history of development, the writers had a strong belief that this is true. Not only was he always a leading figure in the forefront, but he conveyed strong messages on the role and importance of the soil mechanics and foundation engineering every time he participated in the ICSMFE. We are very much impressed by his enthusiastic and heartfelt message to our community.
No less important was the role played by Arthur Casagrande. He was instrumental in persuading the President of Harvard University to host the conference and carrying out all arrangements for organizing the first International Conference on Soil Mechanics and Foundation Engineering. The great success of this conference contributed greatly for establishing the place of soil mechanics in engineering practice throughout the world. He also dedicated himself to the ISSMFE as the 3rd President between the periods of 1961 in Montreal to 1965 in Paris.
There is a saying that for a great religion to be established, there always are two key-role playing giants. For Christianity Jesus Christ is the originator and his disciple Saint Paul was the great evangelist. For Greek philosophy, Socrates was the great philosopher and it was Plato who was the greatest disciple. Terzaghi and Casagrande are considered as a combination in the same context. Without Terzaghi, Casagrande would not have been so well-known. Had there not been Casagrande, the fame of Terzaghi would have developed in a different format.
Now neither I nor the authors are suggesting that soil mechanics is a religion, but their point on the timing and combination of Terzaghi’s and Casagrande’s work was critical to what we see as the field of soil mechanics/geotechnical engineering today. Without these two and others seeing a need, taking charge, and filling that need, we could very well be viewing things from a completely different framework.
So as we reflect on this celebrated day, let’s remember not only Prof. Terzaghi’s great technical achievements, but also his role as a leader (along with many others) shaping our field of practice and our professional societies.
The Deep Foundations Institute is pleased to announce Dan Brown, P.E., Ph.D., as the recipient of the DFI 2011 Distinguished Service Award. The award, in its 31st year, honors individuals chosen by their peers for exceptional contributions to DFI and to the industry.
Brown began his career with a B.S. from Georgia Tech, and later received his Ph.D. at the University of Texas, Austin, in only 28 months, while working. He then taught at Auburn University for 22 years before setting up his own consulting firm in Tennessee. The Winter 2011 issue of the DFI magazine included a profile of Brown that chronicled the universal admiration and regard for him within the industry. He was cited by others for his expertise, his intelligence and ability to teach others. Brown and his firm are sought out for advice everywhere.
A piled raft refers to a shallow foundation that is structurally connected to the piles, while composite ground refers to a soil-pile matrix where the piles are not structurally connected. The design objectives for both a piled raft and composite ground are (excluding special considerations such as expansive soil): (1) to provide a sufficient ultimate resistance and (2) to distribute the load into the soil-pile matrix so that the settlement experienced by the shallow foundation is within tolerable limits. A simplified model is proposed for a shallow foundation on composite ground where the foundation settlement is estimated as the sum of the downward movement of the piles plus the downward movement of the shallow foundation relative to the pile head. The proposed simplified model is applied using conventional geotechnical analyses for two hypothetical examples of shallow foundations undergoing compression settlement.
This paper was originally published in DFI’s bi-annual journal, Volume 5, No. 1 in June 2011. DFI is an international technical association of firms and individuals involved in the deep foundations and related industry. The DFI Journal is a member publication. To join DFI and receive the journal, go to www.dfi.org for further information. ”
The planned second load test in the ADSC research project for rock sockets in the Southeastern U.S. is moving closer to execution. Bruce Long of Long Foundation Drilling Company provides this update:
To Fellow Load Testers,
We want to thank everyone who submitted questions or comments regarding the preliminary load test program submitted to us by Dr. Dan Brown. Those comments, and more, will be considered while fine-tuning the program.
Because we have several companies donating their time and money, we have to be flexible with respect to the installation and testing dates. We have tentatively selected some dates, but these are subject to change depending upon the workloads of those volunteering their efforts. We hope to begin shaft installation during the last two weeks of July (weeks beginning the 18th or 25th). The actual load testing would probably take place the week of August 8th, with the actual test date being decided upon by sometime in early July (I hope to give everyone at least a 3-4 week notice).
The actual test date would include a field day visit by all interested parties to the test site at Foundation Technologies office in Lawrenceville, GA. Activities will include a load testing discussion led by Dr. Dan Brown, along with lunch. We would then move to the test site where Loadtest, Inc. will be conducting the Osterberg Load Test on our first shaft. A discussion of the testing process and procedures by Loadtest will precede the actual testing (We will be submitting information later regarding a load test contest where each of you will get to predict the outcome of the test with a special prize going to the winner). We also hope to be drilling on the second shaft that day and will be discussing the drill rigs, tools, and other equipment being used, as well as having the other Osterberg cell available for viewing. This site visit proved to be very well received when we did it in Nashville at the last load test. We hope for a big turnout that day.
I wanted to give everybody a brief update and will be in touch when additional information becomes available in the near future. Thank you for your interest, and if anyone has any questions regarding this plan, please feel free to call me at your convenience.
Paul gave a presentation recently at the Iowa ASCE Geotechnical Conference where he discussed two project case histories for LRFD design of bridge foundations. The meeting was held March 3, 2011 in Ames, Iowa. In his presentation, Paul gave an overview of the LRFD design procedure as it applies to foundations, reminding them that LRFD is not difficult and that it provides a logical framework for incorporating reliability into foundation design. Paul talked about our experiences using LRFD for foundation design for two bridges over the Mississippi River: the Hastings Bridge in Hasting Minnesota and the new I-70 bridge in St. Louis, Missouri. Both bridges are currently under construction.
A PDF of his presentation can be found at the link through the image below, or on our Presentations page.
On December 29, 2010, Audubon Bridge Constructors recently “closed” the main span of the John James Audubon Bridge between New Roads and St. Francisville, Louisiana. Watch the video featured at the top of the page at the bridge link to hear about the bridge, including the drilled shaft foundations! For something really fascinating, go to the webcams here and scroll back through the various dates. They have archived images all the way back to start of construction.
Photo: Chris Usery, Figg Bridge Inspectors
The last cables were installed on January 3, 2011 as noted on the project website:
The last two cable stays of the longest cable-stayed bridge in the Western Hemisphere were installed on January 3, 2011, five days after the spans were connected. The John James Audubon Bridge, Louisiana’s newest crossing over the Mississippi River, now has all of its 136 cable stays in place.
This bridge will be the longest cable-stayed bridge in North America when it opens later in 2011. Again, from the project web site:
The spans of the longest cable-stayed bridge in the Western Hemisphere were connected on December 29, 2010, stretching 1/3 of a mile over the Mississippi River. The John James Audubon Bridge, connecting Pointe Coupee and West Feliciana parishes in Louisiana, is approximately 92% complete. Construction of the spans began from both sides of the 500-foot tall towers earlier this year. Both sides continue to progress at a rapid pace, and now the meeting of the spans has occurred.
Steve Dapp and I had the pleasure of working with many great people during our time on site (much more time for Steve than for me!) during foundation construction. One of them, Chris Ursery of Figg Bridge Inspectors, has been great about providing us with photos now and then to keep us updated of some of the details of the bridge construction. Chris has granted us permission to share a few of his recent photos, which are shown below or can be seen in our web albums here.
DBA is part of a team led by Parsons Transportation Group that was selected to design the replacement of the Hurricane Deck Bridge over The Lake of the Ozarks in Camden County Missouri. MoDOT has awarded the design contract to Parsons. DBA will be the lead geotechnical engineer with Terracon on the team providing drilling and laboratory services, as well as some foundation engineering support services. Parsons was chosen due to the innovative approach the team proposed that includes reusing the existing piers (from ENR.com):
MoDOT chose Parsons for proposing an innovative approach to construction that involves the use of temporary pier widening and shifting the existing superstructure over. This method will allow traffic to be maintained on the existing bridge while the new bridge is constructed, potentially resulting in significant cost savings.
Hurricane Deck Bridge of Ozarks crosses the main channel of the lake of approximately mile marker 35. It carries Missouri highway 5 between Versailles and Camdenton. It was built in 1936 –five years after the lake filled. It was named as Hurricane Deck because it was heard that a tornado struck that area which was locally "Hurricanes". It is a nautical term associated with river steamboats. The Hurricane Deck was the uppermost deck which provides and allows everyone to experience the pleasant breezy place and the passing scenery.